Mice or joy sticks are frequently employed as an input control device for a computer. The use of a mouse or joy stick may enhance the operability of a computer in that it permits angle signals for two directions of X and Y axes to be concurrently generated, thereby ensuring smooth movements of a cursor.
The mouse generally comprises a single spherical control member and two rotary encoders for detecting the rotation in X and Y directions, the encoders being in operative engagement with the control member to move the latter in desired directions to thereby generate angle signals for X and Y directions.
The joy stick comprises a control lever supported vertically by a console and is configured to generate angle signals as the lever is tilted in a desired direction to bring the contact located in that direction into contact with the corresponding one.
The mouse is capable of producing angle signals having a high resolution since such signals are generated by rotary encoders. It is also able to produce velocity signals depending on the speed at which the spherical control member is moved in rolling motions, whereby the speed of movement of a cursor appearing on a monitor may be varied. While the mouse is superior as an input device in these respects, the drawback thereof is the complicated and expensive implementation.
On the other hand, the joy stick has the disadvantage that it has a coarse resolution for the angular direction because no more than about 4 to 8 contacts are disposed around the control lever. An additional drawback is the inability to generate any signals corresponding to the operating speed. If velocity signals are to be generated corresponding to a force with which the lever is operated, it would be required to use expensive components such as pressure-sensitive rubber members and strain sensors, resulting in an increase in the cost of manufacture. In addition, with the arrangement in which the operating force is sensed by pressure-sensitive rubber members or strain sensors to produce velocity signals, the sensed signals will be output as analog signals. However, such analog signals must be passed through an A/D converter before they can be input to a computer, causing a further increase in the cost.